The present invention relates to tool or material positionment machines with precision motion control as may be used by industrial robots, material processors and transfer facilities. There are numerous industrial tasks that require a tool or workpiece to be translated from one position to another along a prescribed path. Definitively, translation is a positional change of spacial coordinates without rotation. Most restrictively, such industrial process translation is required to be in a substantially straight line or constant plane.
U.S. Pat. No. 5,222,854 issued Jun. 29, 1993 to L. D. Blatt et al is typical of numerous prior art translational mechanisms. In this example, the objective is to remove a sheet metal stamping from the platen of a first press, translate the stamping to a conveyor carried support cradle which delivers the stamping to a second press where a second transfer machine removes the stamping from the conveyor cradle and positions it upon the second press platen. The Blatt et al transfer machine pick up tool is supported by a four bar parallelogram linkage wherein the parallel links, which support the tool carrier in a level plane at their lower end, are pivotally secured at their opposite end to a vertically adjustable pivot mount and also pivotally secured at the respective mid-spans to a horizontally adjustable pivot mount. Both pivot mount adjustments are motor driven and controlled by programmable microprocessors for simultaneous pivot position changes to translate the workpiece over the desired, straight line path.
U.S. Pat. No. 4,589,819 issued May 20, 1986 to S. Shirao also provides a sheet metal work piece handling machine for loading and unloading presses. Shirao also pivotally connects his tool holder to the lower end of a four bar parallelogram linkage. The upper ends of that linkage are pivotally secured to a position adjustable pivot mount which is vertically translated by a strut motor. The tool holder is laterally translated in a horizontal plane by a strut driven crank arm having one end pivotally connected to one of the parallel links.
U.S. Pat. No. 4,451,196 issued May 29, 1984 to Yutaka Harada describes another transfer mechanism having two, four bar linkages compounded end-to-end wherein the distal ends of one linkage pair are pivotally connected to the distal ends of the other linkage pair. However, one of the pivotal connections includes a plate cam and follower arrangement which provides a variable length to the link that is common to the two linkage pairs. The invention objective is to provide a constant translational plane for the tool holder.
U.S. Pat. No. 3,168,184 issued Feb. 2, 1965 to S. N. Gavin is directed to an apparatus for orthogonally translating glass sheets from one conveyor to another. A control parameter for the Gavin apparatus is that the sheets travel in a "uniform parallel plane in order to avoid the induction of any turbulent flow which may cause cracking of the glass sheets." To accomplish the objective, the glass plate pick-up tool is positioned at the end of a vertical axis hydraulic cylinder. The cylinder is carried at the outboard end of a four bar parallelogram linkage disposed exclusively for horizontal swinging movement. Vertical movements of the glass sheet are controlled linerally by the fluid strut.
It is an objective of the present invention, therefore, to provide a four bar, parallelogram linkage assembly for translation of an arm end mounted tool along a line substantially perpendicular to the assembly base, such translational movement respective to a single plane being powered by a single motor alignment.
Another object of the present invention is to provide a horizontally swinging, plate material transfer boom that may be raised and lowered along linear vertical paths by a single linear strut motor.
A still further object of the present invention is to provide a linear displacement distance of reasonable length by a compounded organization of pivotal links.